I'm facing a problem I can't explain and I would like to know if someone has more information about it.
I'm drawing a solar system and when I plot earth with the Horizon cartesian coordinates, it does not match the orbit plotted via the Horizon orbital elements.
Here is the answer
2458055.500000000 = A.D. 2017-Oct-29 00:00:00.0000 TDB EC= 1.693936505240274E-02 QR= 9.828535727121969E-01 IN= 1.619499879517213E-03 OM= 1.180185004251146E+02 W = 3.460022671282024E+02 Tp= 2458123.158659660257 N = 9.859206292830410E-01 MA= 2.932939316914255E+02 TA= 2.914962922586066E+02 A = 9.997893698231427E-01 AD= 1.016725166934089E+00 PR= 3.651409548675242E+02
I'm using EC and A to plot the ellipse. Here are my calculations : Center of ellipse X : -EC * A Center of ellipse Y : 0 Radius of ellipse X : A Radius of ellipse Y : A * sqrt(1 - EC^2)
And here is the answer :
2458055.500000000 = A.D. 2017-Oct-29 00:00:00.0000 TDB X = 8.085189297377026E-01 Y = 5.770742450594002E-01 Z =-2.783714659030374E-05 VX=-1.027876320855459E-02 VY= 1.393441165141858E-02 VZ= 7.146303246417249E-08 LT= 5.737033579585715E-03 RG= 9.933365717771512E-01 RR=-2.711916121500719E-04
I'm plotting earth at the given X, Y, Z coordinates
And I don't understand the result. Earth is almost on its orbit but not exactly. It's off by 1,275... % and I don't understand why.
Is it because the keplerian elements are approximations or is it because my drawing of the orbit is not very well made atm ? In other words, should the earth be exactly on its orbit when using the Horizon data or is this error expected ?
Thank you very much